HONG KONG, Aug 31 (Reuters) - Volkswagen AG could reach a “final” settlement with U.S. authorities as early as October over its large-engine diesel cars found to have cheated emissions tests in a global scandal, the sales chief of its premium Audi brand said.

Dietmar Voggenreiter, head of sales and marketing worldwide for Audi, told Reuters in an interview in Hong Kong on Wednesday that negotiations related to 3.0-litre engine VW and Audi cars were progressing well.

“(We‘re) in really good discussions with U.S. authorities,” said Voggenreiter. “Hopefully in October, latest the beginning of November, we will have the final agreement with the U.S.”

The worldwide scandal, dubbed “Dieselgate”, has hurt VW’s reputation and business, and already cost the German carmaker billions of dollars - not including any U.S. settlement on the large-engine diesel vehicles.

The diesel emissions scandal, affecting roughly 11 million vehicles worldwide, continues to drag on VW and Audi profits, with Audi set to miss profitability targets this year and the core VW brand recording a 12 percent year-on-year drop in profit in the second quarter.

VW last September admitted using sophisticated secret software in cars to cheat on exhaust emissions tests. The firm agreed with U.S authorities in June to pay up to $15.3 billion for car buybacks and fixes to 475,000 2.0-litre VW and Audi diesel vehicles fitted with the emissions-cheating software.

That accord did not include fixes for around 80,000 VW, Audi and Porsche 3.0-litre engine cars that could potentially cost billions more if the automaker needs to buy them back.

Voggenreiter said on Wednesday that the U.S. negotiations, which related to four-cylinder VW diesel cars and 3.0-litre V6 engine Audi vehicles, were still ongoing and unresolved.

“We are just in discussions so I cannot judge how the authorities will judge our technical solutions; but I feel we have good technical solutions,” he said. (Reporting by Farah Master in HONG KONG; Writing by Jake Spring in BEIJING and Adam Jourdan in SHANGHAI; Editing by Kenneth Maxwell)